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Sorry, f4 thread, not wheels.
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A wheel like that in 99 f4 would obviously be grippier than classics. That fact about friction does not work with skate wheels. We are grinding the wheels down, wider contact patch means more material to wear down, which means more grip.
That does not count as backing your claims. You are just asserting that the surface area does affect the grip.
And since you don't back your claims up, we can just continue to ignore them.
Engineer here with a background in physics, applied science and applied maths. I've done the maths, was a while back but did it nonetheless.
More area = more grip as the coefficient of the material has an exponential curve based on force (aka rebound).
Breaking into a slide will be more difficult but maintaining said slide will be easier. Vice versa on the smaller surface wheels.
That being said, we are working with very small margins when comparing same compounds. Biggest difference you could make is based on weight and the angles/force you approach the slide. Also wider wheels will be more controllable as it would want to normalize quicker, and smaller wheels will be more difficult to normalize.
I know this is difficult to understand, cant argue the theoretical science, but there is a big difference in theoretical science and applied (assumptions/fixed variables).
So what you are saying is that the coefficient of friction is not constant with skateboard wheels but increases exponentially with increasing force? Or increasing force per unit of area? But the force stays the same. Force per unit of area decreases with increasing area. Are we talking about deformation of the wheel material under applied force here? If skateboard wheels were to deform enough under force to make a difference, wouldn't a narrower contact patch then provide more grip due to it deforming more as the force per unit of area is greater with a narrower contact patch?
Can you provide some more info on what you're saying as it's the first time I've heard of such and didn't really understand what exactly you were trying to say?
I'm not an expert, but I've read a bunch about contact patch vs friction on racing tires and what I can see is that dynamic friction for objects that deform is a complicated science and there are deviations from the normal models of friction, especially when you look at the shape of the object and how energy and vibrations dissipate. Also transferring energy among something with rolling inertia plays a roll (pun!). I'm not saying the opposite of what you are saying is true, it's just a murky area until we start stacking up peer reviewed studies on powerslides because of all of the variables in real world situations.
Friction with deforming materials sure isn’t as straight forward as friction with essentially non deforming materials. Car tires are far softer than skateboard wheels though and have 10+ times as much force weighing down on them and are filled with air. They’re pretty much engineered to deform to increase grip. I don’t think the deforming argument really applies to skateboard wheels. Even with car tires it’s not apparently all that straight forward that wider tires will increase grip. I’m no expert on that but I think the width is more related to tire durability, that it doesn’t rip apart so easily with the forces it has to withstand.
Haha. Sorry but this is very difficult to explain, hence the theoretical vs applied science. I also work for a living now and dont really dive into these things so much anymore.
Theoretically the the friction coefficient is linear and keeping force (weight) the same the contact area will have no effect.
In practicality, the friction coefficient is not (or rather the equation), there are other forces at work aka wind/drag, magnetic forces between the materials (wheels and surface) as well as the digging into the surfice (small wheels will dig more into the surfice), even deformation due to these forces on the wheel. Now all of a sudden this simple equation of frictional force become a new beast and the wheel shape/size plays a bigger role. You can argue each force individually but in the end bigger = more friction.
This is why F1 racing cars have bigger conical fulls and not biscuit wheels, deformation, drag, digging into materials actually makes a big difference on total friction. More so on racing than skateboarding wheels but the same principle applies.
The human body is crazy though, you can feel the difference. I have F4 classics 53s and lock in 55s. The 55s slide way nicer but with more effort than the classics.
Hmmm. Explanation is very vague. You're saying that because of wind/drag and magnetic forces wider skateboard wheels have more grip? Gotta say, I don't buy it. Also wouldn't a narrower wheel digging in the ground cause it to have more grip?
And you're saying that the same principles apply to deforming air filled soft rubber wheels on racing cars and essentially non-deforming hard polyurethane wheels on skateboards? Based on everything I've know about this subject racing cars have wider wheels not because they provide better grip but because they provide better structural integrity and also don't overheat nearly as easily as narrower wheels.
Damn. Believe what you want to bro but if you want to learn something keep reading though.
First of all, yes a narrower wheel will dig into the ground more but that is just one part of the strengths that's being introduced to the wheel, there are many and straight friction is also just a small part of it, i was just trying to bring to light a few (positives and negatives). Again when all is considered and a mathematical model is built, a wider wheel will give more "traction"!!! Now again please understand that the to biggest variables are force and angle of attack. Drag,magnetic strengths etc adds up but is marginal.
Also a polymer is a semi liquid, air and liquid act very much the same under pressure, go ride harder and softer wheels then come tell me deformation has nothing to do with it?
Now for the last time, breaking into a slide will be more difficult with a wider wheel but when sliding the mother fucking equation changes. In fact, i believe because its a harder type compound, when sliding a wider wheel will go further
Thus I agree with @firebert, my lock-ins out perform my classics in sliding, they are however ever so slightly more difficult to get into a slide.
I’d love to keep reading about this. Can you suggest me some reading that support your views? I can go get some books from the university library or ask some friends who are still at university to get me the articles if you can point me in the right direction.
Also what the hell does angle of attack have to do with friction between two solid surfaces? 🤨
While polyurethane is semi crystalline equating polyurethane wheels to air filled rubber tires seems pretty crazy to me. Also saying that liquid and air act very much the same under pressure leads me to believe you don’t have a very strong grasp of physics. Gases are compressible while liquids are essentially not. That’s quite a difference. 😮
I’ve ridden hard and soft wheels plenty. Do tell me how riding them can make me assess the impact deformation has on grip in skateboard wheels cuz it isn’t exactly evident to me.
It seems to be that you’re just throwing out semi-related fancy terms at me and saying “it is how I say it is because I said so” without actually backing it up in any way.
You seem like a guy who like to argue just to argue but ok.
If you want to read up and get up to speed. There are 3/4 field areas which you require basic understanding of.
Applied physics (basic physics to understand the forces)
Applied engineering maths (apply the physics learning into maths)
and advanced engineering modeling (to build the mathematical models, this will give you the answers you seek)
Material science will also benefit you it seems (as gasses and liquid does act the same under pressure although liquids to a much much smaller degree - when doing the calcs you can't go well, "liquids/solids" "essentially" does not compress or deform because they do - 99 duro vs 101 vs 80 etc.) Polyurethane is also a liquid and solid at the same time but ya, not going into that subject either.
Please dont mix theory with applied science as there is a difference.
Also riding a softer wheel is less bumpy, slide more difficult and goes through cracks easier etc. we also call this deformation due to compression (they deform to the surface more), they will be slower because there is a bigger area in contact with the surface at all times, aka more magnetic forces between the wheel and surface, more horizontal forces etc..i've gone through this jesus..
There are more than enough material available anywhere. Internet or library.
With angle of attack please go draw a 90 degree triangle. Go look at the vertical and horizontal lines, those 2 are some of forces at work, both plays a big role in all of this. I'm going to stop here now as its stupid to try and explain all this.
If you are really interested go study applied engineering maths, it should give you the basics aka. bullet of size z and weight x traveling at this speed y and angle xyz hits a block of wood on a train going at this speed z, the block of wood is this size x and weight y on this surface type, go calculate what happens to the block. This will give you an idea of friction forces but not the material forces, deformations etc. there is a lit more than just this but this will give you a starting point.
I was very hesitant to post this because there is no point but here you go. This will be my last post about the subject.
Topic: The Set-up Thread (Read 5899135 times)